/* media queries which are guaranteed to evaluate to true */
@media all

and (           min-width:
    1px),

    (max-width: 1000em


) { }

/* media queries which are guaranteed to evaluate to false */
@media all and (max-width: 0px), (min-width: 1000em) { }
@media (min-width: 20px) and (max-width: 10px) { }
